INTERLEUKIN-10 INHIBITED THE EXPRESSION OF TUMOR-ANTIGENS AND MAJOR HISTOCOMPATIBILITY COMPLEX ANTIGEN ON EJ-RAS ONCOGENE TRANSFORMANTS

Interleukin-10 (IL-10), a novel inhibitory cytokine, is one of Th-2 (T helper) cytokine. It inhibits mixed lymphocyte reaction, and the prod uction of inflammatory cytokine and monokine downregulates major histo compatibility complex antigen (MHC) class II antigen expression. Howev er, the effect of IL-10 on tumor cells is not known. Therefore, the me chanism of tumor tolerance induced by IL-10 was investigated. (WKA rat fetus-derived fibroblast) (WFB) and W14 and W31 (EJ-ras oncogene tran sformants of WFB) were cultured with recombinant human (rh)IL-10 (0, 1 0, 50, 100 ng/ml). FAGS analysis was performed using the following mon oclonal antibodies: anti-rat MHC class I monoclonal antibody; and mono clonal antibody 109 (anti-natural killer [NK] target molecule on W14). Monoclonal antibody (mAb) 109-defined antigens were newly expressed d uring the transforming process by EJ-ras oncogene transfection to WFB. In addition, the effects of rhIL-10 on the ability of proliferation a nd susceptibility to NK cells were assessed. The cultivation with rhIL -10 resulted in a dose-dependent decrease in the expressions of MHC cl ass I antigen and monoclonal antibody 109-defined antigen. The prolife ration and susceptibility to NK cells of W14 were inhibited. These dat a demonstrated a possibility that IL-10 could induce tumor tolerance t o host immunity by inhibiting the expression of tumor-associated antig ens and MHC class I.